Question: $ { \left[\begin{array}{rr}{2} & {4} \\ {2} & {-2}\end{array}\right]-\left[\begin{array}{rr}{-1} & {-2} \\ {-1} & {1}\end{array}\right] = {?} } $
Explanation: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}-{-1} & {4}-{-2} \\ {2}-{-1} & {-2}-{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {6} \\ {3} & {-3}\end{array}\right]}$